117
FXUS61 KCTP 020001
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
801 PM EDT Mon Jul 1 2024

.SYNOPSIS...
A large high pressure system will build into the region tonight
and Tuesday, followed by a dying cold front pushing in from the
Great Lakes and stalling out over the area by the middle of
next week. Very warm and quite humid air will return for the
second half of this week and last into the weekend.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Surface high pressure and associated low-pwat air mass building
over PA tonight will result in efficient radiational cooling and
min temps several degrees below seasonal normals. Have undercut
NBM low temps by a couple of degrees, with expected daybreak
readings ranging from the mid 40s in the cooler valleys of the
Alleghenies, to the low 60s in the more urbanized spots of the
Lower Susq Valley. Despite very dry air over the area, expect a
large air/water temp difference of >25 degrees to result in
patchy late night fog in the deep river/stream valleys north of
I-80.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
Upper level ridging building into PA from the west will result
in fair and warmer conditions Tuesday. However, the surface high
and associated low-pwat air will remain parked over the state,
so expect humidity to remain low. Mixing down model 850mb temps
of around 13C translates to expected highs ranging from the mid
and upper 70s over the higher terrain of the Alleghenies, to
80-85F in the valleys. Very dry air above a weak inversion the
forecast soundings is a reliable indicator of dewpoints falling
below NBM guidance, so have leaned toward the lower MAV/NBM10pct
numbers. Warm advection aloft ahead of a weak shortwave
cresting the top of the ridge will likely produce some thin
cirrus Tuesday, but sunny to mostly sunny wording should
suffice.

The warmup will continue into Wednesday with an uptick in
humidity as the surface high drifts off of the Mid Atlantic
coast, accompanied by a return southern flow. GEFS 2m temp
anomalies are a few degrees above normal over the W Mtns and
near average elsewhere, translating to highs well into the 80s.
Moisture advection ahead of an upstream cold front could
potentially support a shower/tsra toward evening across
Warren/Mckean counties. Otherwise, upper level ridging should
ensure another mostly sunny, rain-free day across Central PA.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Despite the arrival of a cold front near the beginning of the
long term (Thursday-ish), heat builds and then lasts for the
rest of the long range period. The front likely won`t cleanly
pass through the state and will linger nearby for the end of the
week. The highest confidence of precip and storms is Wed night-
Fri, both due to the near-ness in time and presence of the front
and flattening/lowering heights. We could eek out a dry day on
Sunday. But, the PoPs are in the chance (30-50pct) range for
each day after - mainly for diurnal storms. At this point, the
SE half of the area may be the best place to get wet with those
pop-ups each day. That would be good news for them as they are
currently the driest in the CWA (and in D1 drought status). The
flow stays generally out of the SW, and should be drawing
moisture and heat from the southern states if not the whole
GOMEX for the first half or more of next week. Thus, there isn`t
much change in the hot temps and muggy dewpoints through the
whole of the long range. 8H temp anomalies of +2C to +5C will
make maxes in the M80s to L90s common. The heat risk for the
period looks worst on Fri and Sat when heat index values get
around 100 for the SE/Lower Susq, esp in the urban heat islands.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
VFR conditions and mainly clear skies will prevail tonight and
Tuesday. There is a very small chance (<20%) that patchy valley
fog will impact airfields in the NW mountains. No mention of fog
has been made within the TAFS due to low probabilities. Winds
diminish this evening as the center of high pressure builds over
the region.

Tuesday is expected to remain dry with fair weather and light
winds to persist until Wednesday night.


Outlook...

Tue...Patchy AM valley fog N Mtns.

Wed...Evening tsra impacts possible NW Mtns.

Thu...AM low cigs possible W Mtns. Sct PM tsra impacts
possible.

Fri...Sct tsra impacts possible, mainly PM.

Sat...Chc tsra throughout the day.

&&

.CLIMATE...
June 2024 was the warmest June on record for Bradford with a
mean temperature of 66.6F, breaking the old record of 65.8F set
in 2021.

June 2024 was the 3rd warmest June on record for Harrisburg with
a mean temperature of 76.0F.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Lambert
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Dangelo
AVIATION...DeVoir/Bowen
CLIMATE...Colbert